Embedded System: Which platform or board?

I want to build a portable system / device for processing guitar effects (own pod)

I need: touchscreen (as main input) ssd / sd card or other? intel pentium i3,5,7? (needs power for processing realtime effects network (bluetooth, wlan, ethernet ...) (for control, configuration ...) audio input / output (for the guitar / recording ...) linux transportable (no big power supply, with rechargeable batteries and also usb and normal power supply)

i would write the application running on the system with c++ in qt

I saw many interesting boards like arduino, beagleboard, hawkboard and some m开发者_如何学Cini / micro itx embedded systems, but now i dont know anymore which one i should choose

should also be easy to develope for and not so expensive

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There is an Arduino project doing that. Take a look. If you need more power then you will need something like ARM or some DSP microcontroller.